axTicksByTime: Compute x-Axis Tickmark Locations by Time

Description

Compute x-axis tickmarks like axTicks in base
but with respect to time. Additionally the first
argument is the object indexed by time which you
are looking to derive tickmark locations for.

It is possible to specify the detail you are seeking,
or by passing 'auto' to the ticks.on argument,
to get a best heuristic fit.

the object indexed by time, or a vector of times/dates

ticks.on

what to break on

k

frequency of breaks

labels

should a labeled vector be returned

format.labels

format labels - may be format to use

ends

should the ends be adjusted

gt

lower bound on number of breaks

lt

upper bound on number of breaks

Value

A vector of index points to break on, possibly with the index names.

Details

This function is written for internal use, and documented
for those wishing to use outside of the internal function
uses. In general it is most unlikely that the end user will
call this function directly.

The format.labels allows for standard formatting like
that used in format, strptime, and strftime.

# NOT RUN {data(sample_matrix)
axTicksByTime(as.xts(sample_matrix),'auto')
axTicksByTime(as.xts(sample_matrix),'weeks')
axTicksByTime(as.xts(sample_matrix),'months',7)
# }